Engine choice for W114 230.6

[faisal]

Hi everybody

I am completely new in here. I have recently bought a 1975 W114 230.6 (my first MB) which has a Toyota engine installed. I am from Bangladesh and these are rare cars here. I am looking forward to putting in original engine and the limited choices i have are M123 early version or M102 from one MB enthusiast here.

The M123 does not have the original Solex carburetor. A small Toyota carburetor is being installed with modified base on top of manifold.

The alternative is one fuel injected M102. We don't know from which car it is coming from. I am considering the M102 since this may provide better fuel economy with similar output.

These engines are very difficult to find and are quite expensive here.

Need your advice on what should be my choice and what are challenges in putting in M102.

[Frank Reiner]

Since the original M180 engine is gone, the closest to the original would be the M123 (2.5L version of the M110).

What transmission is in the car now, and what MB transmissions are available to you?

The M102 will require its own transmission, and quite a few changes to the fuel system to accommodate the injection.

Is the car left hand drive (LHD), or right hand (RHD).

[faisal]

The car is RHD with power steering.

The M123 comes with the 4 speed manual transmission for the engine. Without the original carburetor I am not sure what are the problems I should be expecting. I have been told that I would get better fuel economy. The car will be driven in city in heavy traffic. I plan to go for either original or Weber carburetor in future. But would be difficult to do that immediately for budget issue.

The M102 doesn't have a transmission and I would have to source one. I understand I need to have fuel pump installed. But completely unaware of the other challenges. The person from whom I may get this also suggested that he may replace the fuel injection with a carburetor by installing a different manifold. Don't know what would be drawbacks if that is possible at all.

[Frank Reiner]

I rather expected that the car would be RHD. Given that, the M102 may be easier to install. Is the car currently equipped with manual transmission? If so, both 4 and 5 speed manual transmissions are available for the M102.

A carburetor equipped M102 would simplify the fuel system. M102 engines were supplied with carburetors outside the USA (which is where I am located). With respect to the matter of installing fuel injection, it is not just a pump change/addition, but it also requires that all the fuel line connections be upgraded to withstand pressure of about 5 bar, as well as the wiring and Engine Control Unit (ECU) required to operate the mixture control.

With respect to the M123 Solex carburetor, its absence is no great loss. Almost any other carb will be a substantial improvement. The M123 engine installation would require that the braces between the firewall and the inner wheel wells be removed; the cam box of the M123 interferes with those braces.

[faisal]

Hi Frank
Really appreciate your response. The car currently has a Toyota engine and transmission. Just to summarize my choices

- M102. Needs to be converted to carburation as I don't have the ecu and wiring loom. After the conversion my wild guess is that the output will be somewhere around 105-110 BHP with better low range torque.

- M123. The engine has been started today keeping it on the ground with the different carburetor. Wild guess is that the output would be close to 120BHP. The brace (if i have understood correctly) has been removed earlier for installing the current engine. Certainly this engine would drink more in comparison to M102.

Given the options, probably the M123 would be a better choice for simplicity and for being close to original.

Your comments please.

[Frank Reiner]

Given that the braces have been removed, I agree with you on the choice of the M123. One thing to check carefully is the space available for the exhaust manifold(s), and particularly the location and angle of the exhaust pipe connection to the manifold(s). The space that is available for the exhaust is more restricted on the RHD chassis than on the LHD version.

Where is the battery located? If at the left front of the engine compartment, it may have to be moved to the right to provide clearance for the distributor.
W114 cars with M110 engines had the battery on the right.

[faisal]

Battery is on the right. So no modification will be required.

For the exhaust, i need to have a custom built exhaust pipe as the original one is not available. I plan to have duel pipes going in parallel to retain the original design as much as possible. But thanks as I need to be careful while building the exhaust by checking the available space.

I will continue with the small Toyota carburetor to find out how it perform. And if required will consider a better carburetor in future.

I have already sourced engine and gear mounting, transmission selector and connectors etc. Will retro fit a AC compressor and power steering pump as I don't have the original ones available.

And thanks a lot. Now I am decided on the M123 engine. Hopefully the engine will be installed by end November. I will keep you posted on the challenges and success.